The Portugal international, who has netted 10 goals in his last six games, faces his former club for the first time as Los Blancos host Sir Alex Ferguson's men at the Bernabeu in the last 16 of the Champions League.

Rooney believes Ronaldo, along with Lionel Messi, are the two best players in world football at the moment, but the England international insists the Madrid star needs to be shackled if United are to get a positive result in Spain.

"I played with Cristiano for a number of years and he’s a fantastic player, him and Lionel Messi are the two stand out players in football today," Rooney told GiveMeFootball. "He’s certainly the biggest threat for Real Madrid. He’s an incredible talent and it will be tough to try and keep him quiet, and I’m sure if we can do that it’ll give us a better chance of getting the result we want."

Rooney also pointed to Madrid's other players who could trouble United and admits his teammates must be at their best in order to overcome Jose Mourinho's side.

"Madrid have got a fantastic squad and great players all over the pitch so it’s going to be a very tough game," Rooney said. "Players like Alonso, Ozil and Benzema are all top, game-changing players who can punish you in different ways so we need to be ready and make sure we are at the top of our game."